Preheat the oven to 375°F and line a baking sheet with tin foil. Place the sweet potatoes on the baking sheet and roast for 30-35 minutes (if using fingerlings) or 45-55 minutes (if using small sweet potatoes). When they are done, they will be slightly soft to the touch, but they shouldn’t be mushy. Once they’re done, remove from the oven and let cool.
While the potatoes are roasting, prepare the filling: in a large skillet, heat the olive oil on medium heat. Add the onion and sauté until the onions have softened and are beginning to brown, 12-15 minutes.
Add the corn, black beans, bell peppers, chili powder, ground cumin and lime juice. Saute for 10-12 minutes, stirring occasionally, until the vegetables are cooked through and beginning to brown. Turn off the heat and set aside.
Once the potatoes are cooked and cooled, cut them in half lengthwise. Carefully scoop the flesh out of the sweet potato skin, leaving a thin layer of potato (this helps the skin stay sturdy once filled). Line the skins on the baking tray.
Stir the cooked sweet potato flesh into the corn-black bean mixture. Scoop this filling into each sweet potato skin, then top with the shredded cheese.
Bake the skins for an additional 7-10 minutes, until the cheese has melted and is beginning to brown. Serve with hot sauce, guacamole and sour cream.